Alkyd resins modified with 2, 5-dihydroxybenzoic acid



ALKYD RESINS MODIFIED 2,5-DIHY- 1 DROXYBENZOIC ACID Raymond L. Heinrich, Baytown, Tex., and David A. Berry, Columbus, and Robert L. Christian, Gahanna, Ohio, assignors, by mesne assignments, to Esso Research and Engineering Company, Elizabeth, N.J., a corporation of Delaware No Drawing. Filed Oct. 2, 1959, Ser. No. 843,917

3 Claims. 01. 260-22) invention relates to modified alkyd resins. More particularly, this invention relates to modified alkyd resins of i-mproved hardness and drying characteristics.

Alkyd resins are widely used in the preparation of suriacecoating compositions. A particularly desired class of alkyd resins are the so-called oil-modified.alkyd resins employed in coatings and prepared by the intercondensation of a polybasic acid (preferably dibasic), a polyol, and an unsaturated fatty acid derived from a glycerideoil. d

The present invention is directed to a discovery in the field ot oil-modified alkyd resins which not only permits thCiIlClllSlOll of 2,5-dihydroxybenzoic acid as a raw material;1but which also provides oikmodified alkyd resins of .i mproved physical .and chemical properties.

It; has i now been discovered that alkyd resins composibyrreplacing from about 55 to about 65 mol percent of the.;fatty. acid component of the alkyd resin with 2,5-dihydroxybenzoic acid. In particular, the alkyd resin coating1 compositions of the present invention are characterizedby satisfactory drying times and the films prepared therefrom are characterized by excellent flexibility and hardness.

Alkydresin chemistry'is well known to those skilled in cussed in detail. The preparation and physical properties of, alkyd resins are described in numerousv texts, such as volQIto Organic Coating Technology, Henry Fleming Payne, John Wiley and Sons, Inc.,. N.Y., 1954.

The polycarboxylic acids used in the preparation of the novel alkyds may be any of those generally employed in I the preparation of this type of resin. These acids may .taining from 2 to carbon atoms, such as succinic,

adipic, maleic, phthalic, isophthalic, and the like. Particularly preferred polycarboxylic acids are the aromatic dicarboxylic acids, containing from 6 to 10 carbon atoms wherein the two carboxyl groups are attached directly to the aromatic nucleus. t

In some cases it may be desirable to utilize other -tions; of improved physical properties may be obtained theaartuand, in the interest of brevity, will not be dis- Patented Apr. 25, 1961 "ice I 2 forms of the acidsgsuch as the acid anhydrides or acid chlorides, as phthalic anhydride, isophthaloyl chloride, maleic anhydride, and the like.

The esters of the polybasic acids may be utilized in case the alkyds are to be produced by an ester exchange reaction. Preferred derivatives to be used for this purpose comprise the esters of the above-describedacids and the lower saturated monohydric alcohols, preferably those containing from 1 to 5 carbon atoms, such as methyl alcohol, ethyl alcohol, and amyl alcohol.

The polyhydric alcohols used in the preparation of the alkyds of the invention are those containing at least three 'esterifiable hydroxyl groups. Illustrative examples of such alcohols are glycerol, polyglycerol, pentaerythritol, mannitol, trimethylolpropane 1,2,6-hexanetriol, dipentaerythritol, polyallyl alcohol, polymethallyl alcohol, polyols formed by the condensation of hisphenolswith epichlorohydrin, and the like.

Preferred polyhydric alcohols to be used in the preparation of the alkyds are the aliphatic alcohols possessing from 3 to 6 hydroxyl groups and containing from 3 to 14 carbon atoms, such as glycerol pentaerythritol, mannitol, 1,4,6-octanetriol, and 1,3,5-hexahetri0l.

The polyhydric alcohol (polyol) should contain an average of from about 2.5 to about 4.5 hydroxyl groups per molecule and, per molecule.

A'widevariety of unsaturated fatty acids may be utilized in the preparation of modified alkyd resins, the source of the fatty acid normally being a naturally occurring vegetable ormarine oil. Thus, there may be used the polyethylenic acids derived firom the drying oils,

and their derivatives, such as theiresters, and thelike.

Examples of these acids and derivatives include the acids derived from oilssuch as linseed, soyabean, perilla, oiticia, tung, walnut, and dehydrated castor oil, as linoleic, linolenic, 9,12-octadecadienoic, 9,12,15-oct-adecatrienoic, and elaeostearic acid; the monohydric alcohol esters of the drying oil acids, such as methyl elaeostearate, butyl elaeostearate, ethyl 9,l2 octadecadienoate, butyl 9,l2,l5 octadecatrienoate, and octyl 9,l2-octadeca-" dienoate; the glyceridesof the fatty acids of the drying oils, such as the monoglyceride of the linseed oil acids, the-diglyceride of the soyabean acidsfthe monogly'ceride of the tung oil acids, and the dryingoils themselves,"su'ch as tungoil, soyabean oil, hempseed, sardine, andthe like) The preferred modifiers comprisethe drying oil fatty Particularly pre ferred modifiers are thedrying oil fatty acids containing acids and their monoand diglyceries.

at least 12 carbon atoms. p d

If desired, other modifiers in addition to those described above may be utilized in the'preparation of the novel alkyds. Such modifiersinclude theprotein plastics, natural resins as rosin, synthetic resins as the nitrocellulose, phenol-formaldehyde, urea-formaldehyde and melamine.

type resins, synthetic resins obtained by the addition polymerization of unsaturated compounds, such as styrene, alpha-methylstyrene, vinyl chloride, vinylidene chloride, vinyl acetate, methyl acrylate, methyl methacrylate, and the like, as well as mixtures thereof.

In general, the polybasic acid, polyol, and fattyacid are interreacted in proportions sufficient to provide about a 5 to 25 weight percent excess of polyol. Excess polyol may be defined as that amount of polyol in excess of the amount necessary to combine with the sum of the acid preferablyjabout 3 hydroxyl groups 3 groups in the fatty acid and the 'polybasic acid on a theoretical basis. Alkyd resins are conventionally characterized as short oil alkyd resins, medium oil alkyd resins, and long oil alkyd resins, depending upon the ratio of fatty acid to the dibasic acid in the preparation of the resin. Long oil alkyd resins are normally prepared by the interreaction of about 3.1 to about 3.4 mol equivalents 4 lead naphthenate. For the baked film tests, the cobalt salt" was employed in an amount sufficient to provide0.02"

Weight percent cobalt. I

Table I.--Composition and physical characteristics of glycerine-phthalic-soya alkyd resins containing 2,5- dihydroxybenzoic acid of polyol with about 2 mol equivalents of polycarboxylic acid and 1 mol equivalent of unsaturated fatty acid. Pro- Base gressively larger amounts of polycarboxylic acid and pro- 10 gressively smaller amounts of unsaturated fatty acid are 31 5 zequivalent replace. uti-lized'to provide for'a shorter oil length. Thus, short men 50 60 g o il alkyd resins may be prepared by the intercondensag gglgfi gggggfi 13 tlon'of about 3.1 to about 3.4 mol equivalents of polyol a d u er- 8.2 10.0' 10.0 with about 2.3 to about 2.5 mol equivalents of poly- '15 mkfi'ee" 100 100 100 carboxylic'acid .and from about 0.7 to about 0.5 mol e 8 urs 6 acky 28 410. equivalent of unsaturated fatty acid. 1 x3 6 6 14 Accordingly, the alkyd resin compositions of thepresent 14 y 16 v invention may be defined as intercondensation products ii igigig 16 1 of about 3.1to about 3.4 mol equivalents of a polyol con- 20 a Poor Poor g g taining about 2.5 to 4.5 hydroxyl groups per molecule Boer Poor ()0 with about 2 to 2.5 mol equivalents of a polycarboxylic acid and aboutl to about 0.5 mol equivalent of a modifier From :[ahle 1t W111 h Seen that hhhahsfhctory results consisting'of about 35 to 45 mol percent of an unsatuh chimed Whh zs'dhydroxyhehzolh h when ratedfatty acid and correspondingly from about 65 to than aboutSamol percent of the fatty acid is replaced with 55 mol percentof 2,5-dihydroxybenzoic acid. Thus, imh P Y h hclh- However when the replace proved short oil, medium oil and long oil alkyd resins ment 1s within the range of about 55 to 65 mol percent, A are provided in accordance with the present invention. exceuentfesuhs are ohtamed as 1$ evldenced the y The improvement is most pronounced with long oil alkyd IaPld Ylhg tune o ahoht 3h mmhtes the exceheht h'h i 3Q ness characteristics of the films,'and the good chemical The'invention-Will be further illustrated by the followresistance of the'filmsing'specific'examples which are given by way of illustra- XA 11 tion and not as limitations on the scope of this invention. i i

, Alkyd resins were-prepared by the intercondensation EXAMPLE I of glycerin (95 percent), phthalic anhydride, soya fattyx'ii A 'pluralityx'of' alkyd resins were prepared utilizing acids 2,.4-dihldmXybel1Z0ic acidphthalic anhydride, glycerol, soya fatty acids and, except In Prepaflhg the resin, glass flask was fitted Witha 1 for'the base.resin',.an aromatic monocarboxylic acid. The glass stiffer, a m t a Water jacketed reflux 9 amount of fatty .acid utilized in preparing each of the denser; a a Stark Water p, and an inert gas 1111a resins determined by the extent to which the fatty acid 40 for introducing carbon dioxide below the Surface of was to be replaced, on a molar basis,.by the aromatic monocarboxylic acid. About a .6 to 7 percent molar excess of glycerol was used in order to obtain equivalent material. The reactants were added to the flask, together with an amount of xylenes sufiicient to provide fora comparatively high-rate of reflux. Thereafter, the reac-i degrees of polymerization. tion mixture was brought'to reaction temperature (about All ofthe ingredients were charged at once to a flask Over a Period of about 3 hoursv lendof i' fitted with a reflux condenser connected to a Dean Stark the reaction, the alkyd resin WEIs diluted While hot-With 7 tube. The charge was heated to a temperature of about sfllveht Xylenes to Provide all y containing about 60 450 F. over a 3 to 4 hour period and maintained at this weight percentof resin solids. After cooling, films having i temperature for about 5 to 3. hours. 'An atmosphere of a th c ss of about 0.001 inch ere formed from th refluxing xylene vapor wa aintain d over h cogk alkyd resin withoutthe use of an extraneous drier. .The and vigorous agitation was employed. Water was azeofilms wouldnotdry. The results of this experiment are A 'tropically removed'as evolved during the course of the set forth in Table II. 1 reaction 3 t Table II.--Comp0siti0n and physical characteristicsoff. l of the the alkyd was dhuteh glycerine-phthalic soya alkyd resins containing 2,4 while hotwith solvent xylenes to provide alkyd resin dihydmxybmzm-c acid formulations containing about 40 to 60 weight percent of resin solids. After cooling, air-dried films having a I (ma thickness of about 0.001 inch'ancl baked films of about Mgf'equmlent,ephcemmtv 50 40 0.0005 inch thickness were formed from the resin without h p 23-3 g he use of extraneous driers. The air-dried films were EYgflii j 4 prepared and cured=at 75 F. and 5() percent relative y t me rsto c ree humidityathe baked films werecuredat 250 F. for;30 minutes. ,The films were tested for their physical propwould not yerties.

In Table I there is listedthearomatic monocarboxylic From t e'foregoing it is seen that rapidlydrymg alkyd 5 acid modifiers employed, the extent towhiclrthe fatty resins Which Will form films havlflg excellent P Y$ properties may be preparedby replacing 55 to 65 mol percent of the unsaturated fatty acid with 2,5-dihydroxye benzoic acid. It is further seen that imsatisfactory results. 5 are obtained with isomeric dihydroxybenzoic acids or with lesser amounts of 2,5-dihydroxybenzoic acid. 1

Havingdescribed our invention," what is claimed is; 1. An alkyd resin composition comprising the inter-1e condensation product of about 3.1 to about 3.4 mol; equivalents of a polyol'containing an average of from about 2.5 to 4.5 hydroxyl groups per molecule with acid was replaced with the acid modifier on-a mol percent basis.;ancl the weight percent of acid modifier utilized, basednponthe total charge. In additiomthe drying time of the alkycl' resins prepared in the above-described fashion is given-,- together with the hardness of filmsprepared bydrying of the alkyd'resin compositions. The drier concentration employed forthe air dryingtests was about 0.5 weight percent of lead and about 0.05 .weight,;p rcent of cobalt, based on the, weightof the; resin, solids,- and was added to the alkyd resin as a solution of cobalt and 5 6 from about 2 to 2.5 mol equivalents of a polycarboxylic 3. A11 alkyd resin coating composition as in claim 1 acid and, correspondingly, from about 1 to about 0.5 mol wherein the polyol is glycerol, the dicarboxylic acid is equivalent of a modifier component consisting of about phthalic anhydride, and the fatty acid is soya fatty acids. 35 to 45 mol percent of an unsaturated fatty acid and,

correspondingly, about 65 to 55 mol percent of 2,5-di- References Cited in the file of Patent hygrozybeilifiog: acid. ti l I UNITED STATES PATENTS n a y resin coa 11g composition as in c aim wherein the polyol is glycerol and the dicarboxylic acid is 2197855 Ems 1940 phthalic anhydfide 2,618,616 Tess et a1. Nov. 18, 1952 

1. AN ALKYD RESIN COMPOSITION COMPRISING THE INTERCONDENSATION PRODUCT OF ABOUT 3.1 TO ABOUT 3.4 MOL EQUIVALENTS OF A POLYOL CONTAINING AN AVERAGE OF FROM ABOUT 2.5 TO 4.5 HYDROXYL GROUPS PER MOLECULE WITH FROM ABOUT 2 TO 2.5 MOL EQUIVALENTS OF A POLYCARBOXYLIC ACID AND, CORRESPONDINGLY, FROM ABOUT 1 TO ABOUT 0.5 MOL EQUIVALENT OF A MODIFIER COMPONENT CONSISTING OF ABOUT 35 TO 45 MOL PERCENT OF AN UNSATURATED FATTY ACID AND, CORRESPONDINGLY, ABOUT 65 TO 55 MOL PERCENT OF 2,5-DIHYDROXYBENZOIC ACID. 